Several medical conditions including surgical interventions and trauma can lead to increasing intracranial pressure. These conditions include, but are not limited to: “malignant” cerebral infarction (stroke), brain tumors, epilepsy surgery, and craniosynostosis (congenital cranial anomalies), and brain injury trauma. In the case of brain injury trauma and/or strokes, these medical conditions can lead to a very dangerous effect of causing swelling or edema of brain matter and the enveloping dura within the confines of the cranium. The increased intracranial pressure caused by these conditions is be associated with serious complications including bruising or other damage to brain tissue, delirium, loss of consciousness or cognitive functions, secondary cerebral ischemia or infarctions, brain herniation and possibly death, if left untreated. This situation typically can only be effectively treated by surgical removal of a portion of the cranium (craniectomy) to allow room for the brain to expand and the release of cerebrospinal fluid to reduce the increased pressure.
In the field of treatments for traumatic brain injury (TBI), the current practice in managing acute cases of medically uncontrolled brain swelling is to perform an emergency craniectomy. In this surgical procedure, a flap of cranium is removed from the patient's cranium in order to provide relief to intracranial pressure and reduce the risk of the aforementioned serious or fatal complications. In the established course of treatment, the initial craniectomy producing the cranial opening is followed by a period of intensive rehabilitation. During the entire recovery period, the cranium remains open, and must be shielded by protective head devices or coverings, and the patient's activities may be significantly restricted. The patient also runs a significant risk of infection and other post-surgical problems.
One serious problem that can arise during the post-operative period is the so-called Syndrome of the Trephined. This condition results from the sinking of the dura within the cranial opening due to the negative intracranial pressure relative to the atmospheric pressure which, induces derangements of cerebrospinal fluid flow, cerebral blood flow and brain metabolism, leading to psychological and/or physical deficits in the patient during the recovery period. Once the cranial opening is covered through a separate, later-stage procedure (cranioplasty), documented cases exhibiting the Syndrome of the Trephined have shown a reversal of these deficits with varying rates of improvement. However, the prevailing practice for performing a cranioplasty is to wait for an average of six months or longer after the emergency craniectomy before repairing the cranial opening.
The traditional approach of performing a two-staged procedure of an initial emergency craniectomy followed by a later cranioplasty can be attributed in part to a landmark study carried out by Rish et al. (see Rish, et al., Neurosurgery, 4:381-385, 1979) showing that a shorter time from craniectomy to cranioplasty leads to a poorer outcome. A closer examination of this study by other authors (see Carvi Y, et al., 2006 and Liang et al., 2007, below) however, showed that the cases in the Rish study only pertained to penetrating or open head injuries, ignoring cases of closed (non-penetrating) head injuries that needed decompressive craniectomies as well. In fact, these authors subsequently (see Carvi Y, et al., Neurol Res 28:139-144, 2006; Liang et al., J Craniofac Surg 18:526-532) reported good outcomes after early cranioplasty for non-penetrating head injuries.
Other scientific studies further support performing cranioplasties early after an emergency craniectomy. Data on wartime cranioplasty complications observed during the 2003-2008 Iraq-Afghanistan conflict period (see Stephens F L, et al., Neurosurgical Focus/Journal of Neurosurgery 28(5), 2010) show that the majority of infected cranioplasty cases occurred during a delayed period (90-270 days from injury/craniectomy). Furthermore, multivariate analyses cited the presence of cerebrospinal fluid leaks and repeated operations as the main independent risk factor for the development of craniotomy (brain operation) infections, and not the craniectomy-to-cranioplasty waiting period per se (see Korinek A M et al., Br. J Neurosurg 19:155-162, 2005 and Cheng Y K, et al., J Clin Neurosci 15:1115-1119, 2008).
Further evidence of the benefit of performing cranioplasty earlier after an emergency craniectomy is found from the analysis of craniotomies. In cases where the head-injured require the evacuation of hematomas (bleeding), immediate reinsertion of the skull flap (osteoplastic craniotomy) may be allowable if the result is a quiescent brain (non-edematous). When the intended skull flap has undergone multiple fracture sites and is deemed not to be viable by the neurosurgeon, the skull flap is replaced by commercially available cranioplasty materials (cranioplasty for craniotomies). Wartime data on cranioplasties done for craniotomies analyzed in the same study cited above (see Stephens F L, 2010) show a significantly lower infection rate, suggesting that the period when a cranioplasty procedure can expect the least infection rate would be during the time of the first procedure itself (initial craniotomy or craniectomy).
It follows that, for head injuries requiring an emergency craniectomy due to an edematous (swollen) brain, the optimal period for performing cranioplasty would be during the initial craniectomy. However, all currently available cranioplasty constructs, being rigid, are designed for a late-staged and/or delayed cranioplasty procedure and none are designed to accommodate the initial brain bulging and adapt to the brain movement until the brain contour (and swelling) could normalize. Despite evidence to the contrary and due to the absence of a cranioplasty construct for immediate application after emergency craniectomy, the prevailing practice of a delayed cranioplasty for those craniectomized head-injury patients persists.
It may be desirable to provide systems and methods for a cranial implant assembly adapted for insertion during craniectomy procedure, which, among other advantages, provide the ability to relieve swelling of the brain and dura after a brain trauma or injury by way of a craniectomy, while providing the opportunity to concurrently introduce a cranial implant construct or assembly, during the same initial procedure, with no second-stage surgery required.